In order to realize the increase of the capacity of a matrix converter apparatus, there is a means of employing the parallel multiplex configuration in which a plurality of matrix converters are prepared and the output sides of these converters are coupled in parallel. However, when the output sides are directly coupled in parallel, since the output sides of the respective converters thus coupled in parallel are not always at the same voltage, there may arise a short-circuit between the outputs of the matrix converters. Further, as to the currents flowing through the respective converters thus coupled in parallel, there arises a problem that the current balance states can not be kept same among the respective converters. Consequently, according to the parallel multiplex configuration of the matrix converter apparatus of the related art, as shown in FIG. 7, reactors 51 to 56 are inserted at the respective output phases of the matrix converters thus coupled in parallel, whereby the short-circuit between the outputs of the respective matrix converters is prevented from occurring due to the voltage drop generated at each of the reactors thereby to secure the equalization of the current balance states (see patent document 1, for example).
Incidentally, in order to prevent that the power supply currents flowing through the respective phases of an AC power supply become intermittent due to the on-off PWM control of bidirectional switches in the matrix converter apparatus, in general filter input-reactors 41 to 43 and filter capacitors 61 to 63 are coupled to the respective input phases from the power supply on the input side, whereby the waveforms of the AC power source currents can be made continuous and smooth.
Patent Document 1: JP-A-2003-259647 (FIG. 1)